This invention relates to a system for conveniently and accurately measuring and quantitating the conductive potential of a human body which is based on a determination of lean tissue content. This new application further defines lean tissue content as Total Body Water (TBW) and allows differentiation of Total Water into extracellular mass (ECM) and intracellular or body cell mass (BCM).
Obesity has truly been declared, as of 1985 by the National Institute of Health, a stand-alone risk factor. In fact, obesity has been declared as a disease unto itself. It is now a new medical standard that obesity needs to be diagnosed and treated by a physician for the health and well-being of the general public.
A true definition of "obesity" has been difficult to define, in that such definition is dependent upon a percent body fat determination.
Historically, "percent body fat" has been determined in research laboratories by dunking people in a hydrostatic tank to perform a hydrostatic criterion method for quantification of body fat.
Hydrodensitometry (water tank immersion) has been generally considered to be the traditional standard for body composition analysis. Despite the biological and experimental errors inherent in hydrodensitometry (Lohman, T.G., Skinfolds and Body Density and Their Relation to Body Fatness: A Review, Human Biology, 53: 181-225), all other methods of analysis must be compared to it if they are to be validated.
Another known method for body fat analysis is skinfold measurement (calipers). However, many skilled health care practitioners have questioned this methodology for body composition analysis in that reliability is doubtful. In the hands of trained technicians, anthropometry can give errors of plus or minus nine percent (9%) when compared to densitometry (Katch, F.I., Katch, V.L. (1980), Measurement and Prediction Errors in Body Composition Assessment and the Search for the Perfect Equation. Research Quarterly for Exercise and Support, Vol. 51, No. 1, 249-260). In general clinical use in the hands of a variety of trained examiners with less than expert skill, the error in the caliper technique is presumably even greater.
Recently, body composition analyzers have been introduced that utilize a relatively new technology known as tetrapolar bio-electrical impedance.
Most importantly, through tetrapolar bio-electrical technology, the test/retest reliability has been reported as 0.5% (Lukaski, H.C., Johnson, P.E., Bolonchuck, W.W., and Lykken, G.I., Assessment of Fat-Free Mass Using Bio-Electrical Impedance Measurements of the Human Body) compared to a test/retest reliability of 3.8% for hydrodensitometry.
In this respect, the human body is composed basically of two components--one is lean body mass (Lean Body Mass=Total Body Water+the other listed tissue, Total Body Water=Extracellular mass+body cell mass), which is composed of muscle tissue, connective tissue and bones; and the other major component is body fat. Bio-electrical impedance technology quantifies the true ratio of these components-the difference between lean body mass, which is the healthy metabolizing part, and the body fat, which is the storage of energy in your body. Lean body mass has about 75% water; in contrast, fat is about 3% to 13% water. Accordingly, bio-electrical impedance technology measures the "healthy" part of the body, which is the lean body mass. Lean body mass can also be called Total Body (TBW)+other listed tissues. Total body water is comprised of extracellular mass (ECM) and body cell mass (BCM).
While known tetrapolar bio-electrical technology is considered by many to be an advance from hydrodensitometry both from a reliability standpoint and convenience standpoint, known impedance systems have produced inaccurate body composition analysis in that such known systems are dependent upon a linear regression equation approach. Moreover, much of the data derived from known bio-electrical impedance techniques fails to consider biological data of specific patient groups which may deleteriously affect the accuracy of the body composition analysis.
Accordingly, those skilled in the art have recognized a significant need for an accurate, efficient, valid measurement approach to human body composition quantification. The present invention provides a procedure for quantitative measurement of the conductive potential of the body in a convenient and reliable manner, then through program generated computer screens, solicits sex specific circumference and limb length measurements, and then provides the means for modifying the body impedance measurement with newly created algorithm formula equations that generate scientifically validated predictions of human body composition analysis. The present invention allows the quantification of human fitness or obesity to occur on a significantly wider and more accurate scale than previously achieved.
In addition, the present invention in certain circumstances, includes the gathering of segmental impedance signals and/or multiple, variable frequency impedance measurements. This aspect of the present invention allows the further definitions of body composition into subsets of Total Body Water. The specific means for modifying segmental impedance and/pr multiple variable frequency impedance allows for the objective nutritional and hydration analysis in the outpatient, inpatient and intensive care settings.